Sam, I'm not sure of the answer to getting more range, other than "try the biggest sensor" which is just a guess. I think I understood that the old panasonic sensors had high range, if you can find one surplus, that's a possible idea. I've got a related question about ultrasonic rangefinders. Maybe you can do a quick experiment with yours, and find out the answer. Would an ultrasonic transducer return a different signal (signature) when the pulse was bounced off concrete, versus grass? You mowbot freaks will know where I am going with this. I'd love to have a "concrete sensor" on my 'bot, so the thing won't wander out of my yard out into the street. Sam, if you could simply point your rangefinder at a concrete sidewalk, and then at some grass (preferably from a vertical angle, close range) I'd love to see a scope output (or a sketch) and try to figure out if the differences are stark enough that a PIC could figure out the difference. -- Lawrence Lile P.S. Been working hard on a Mowbot chassis, got it moving last weekend, working on the mower head drive this week! ----- Original Message ----- From: "sam woolf" To: Sent: Monday, April 23, 2001 12:21 PM Subject: [PIC]:ultrasonic range finder I'm a PIC (and electronics) newbie and have just completed my first project.. a sonar rage-finder based on the design at http://www.mindspring.com/~sholmes/robotics/ultrasnd.htm It's working nicely, but I could do with better range. Farnells sell three sizes of ultrasonic transducers/ receivers, and I'm currently using the smallest. Would using the larger size significantly increase the range? Other than the size difference, the specs for all the transducers look very similar. Do any other companies in U.K supply better transducers (though still reasonably cheap ones)? (the ones at Maplins look to me like the small Farnell ones, and RS don't seem to do any) Is there anything else I can try to increase range? Any advice much appreciated! Sam Woolf -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics